Supported olefin polymerization catalysts are of great use in industry. Hence, there is interest in finding new supported catalyst systems that increase the commercial usefulness of the catalyst and allow the production of polymers having improved properties.
Catalysts for olefin polymerization are often based on cyclopentadienyl based transition metal compounds as catalyst precursors, which are activated either with alumoxane or with an activator containing a non-coordinating anion.
Porous inorganic solids have found great utility as catalyst supports. In particular, mesoporous materials, such as silicas and aluminas, having a periodic arrangement of mesopores are attractive materials for use in adsorption, separation and catalytic processes due to their uniform and tunable pores, high surface areas, and large pore volumes. The pore structure of such mesoporous materials is large enough to adsorb large molecules and the pore wall structure can be as thin as about 1 nm. Further, such mesoporous materials are known to have large specific surface areas (e.g., 1000 m2/g) and large pore volumes (e.g., 1 cc/g). For these reasons, such mesoporous materials enable reactive catalysts, adsorbents composed of a functional organic compound, and other molecules to rapidly diffuse into the pores and therefore, can be advantageous over other materials that have smaller pore sizes. Consequently, such mesoporous materials can be useful not only for catalysis of high-speed catalytic reactions, but also as large capacity adsorbents.
For example, mesoporous organosilica (MOS) supports are conventionally formed by the “self-assembly” of a silsequioxane precursor in the presence of a structure directing agent, porogen and/or framework element. The precursor is hydrolysable and condenses around the structure directing agent. See WO 2016/094770 and WO 2016/094774.
MOS supports have shown much potential as supports for olefin polymerization catalysts. WO 2016/094870 discloses the use of MOS supports with olefin polymerization catalysts having nitrogen linkages. WO 2016/094861 discloses the use of MOS supports with olefin polymerization catalysts including phenoxide transition metal compounds. WO 2016/094866 discloses the use of MOS supports with olefin polymerization catalysts having at least one nitrogen linkage and at least one oxygen linkage to a transition metal. WO 2016/094843 discloses the use of MOS supports with olefin polymerization catalysts including metallocene catalysts and/or Ziegler-Natta catalysts.
However, there remains a need in the art for new and improved supported olefin polymerization catalysts that improve the activity and tunability of supported olefin polymerization catalysts.